A telescopic boom type crane is a kind of commonly used hoisting equipment. A truck crane and an all terrain crane are both familiar telescopic boom type cranes. The telescopic boom type crane has such advantageous as good trafficability, good mobility, rapid traveling speed and fast transfer, and thus is more and more widely used in various constructions.
The telescopic boom type crane generally has a telescopic crane boom, a rotary table which can rotate in a horizontal plane, a cable, a windlass, a winding motor, a derricking cylinder and so on. The rotary table is driven by a rotary motor, and a fixed end of the crane boom is fixedly connected at the rotary table. The cable, with a fixed end thereof winded around the windlass and a free end thereof provided with a hook for hoisting goods, is provided along the crane boom. The winding motor can drive the windlass to rotate, and a forward rotation and a reversed rotation of the windlass can control the cable to be tightened and loosened. The crane boom is provided at a base portion thereof with the derricking cylinder, and stretch and retraction of the derricking cylinder can regulate an elevation angle of the crane boom. When it is needed to hoist the goods, the telescopic boom type crane is operated to stretch its crane boom, rotate the rotary table and control the windlass, such that the hook at the free end of the cable is aligned with and hook the goods, then the cable is tightened, the derricking cylinder is regulated, and the rotary table is rotated, such that the goods can be hoisted to a desired position.
During the hoisting process of the telescopic boom type crane, the hook usually swings, thus it is difficult to achieve some hoisting and lowering operations which require high accuracy. If the hook swings seriously, it would threaten personnel safety and property safety.
The hook swings in various forms under different operating conditions, and the swing of the hook mainly includes a longitudinal swing, a transverse swing and a complex swing. The longitudinal swing means that the hook swings forwardly and backwardly in a plane which consists of the crane boom and a projection of the crane boom in a horizontal plane. As shown in FIG. 1, during hoisting or lowering of goods, the goods are not hoisted or lowered vertically because of visual error of the operator or bending deformation of the crane boom, and thus the hook and the goods swing in the longitudinal direction. The transverse swing mainly means that the hook swings in a left direction and a right direction of the crane boom. As shown in FIG. 2, when the telescopic boom type crane is operated to rotate, the hook swings in the left direction and the right direction of the crane boom due to incorrect setting of an actuating acceleration or a stopping acceleration. The complex swing means that the hook swings both in the longitudinal direction and the transverse direction which is resulted from various operating conditions and operations. Whichever kind of swing would jeopardize safe and accurate hoisting and lowering of the telescopic boom type crane.
At present, for some high standard and high accuracy hoisting and lowering operations, it mainly depends on the experienced operator to operate the telescopic boom type crane cautiously and carefully, which process faces potential safety hazard due to relying too much on human factors during operation of the crane.